1. Field of Invention
This Invention relates to tobacco and, more specifically, to a method for reducing nitrosamines in tobacco.
2. Related Art
Nitrosamines, sometimes referred to as N-nitrosamines, are believed to form on tobacco leaves during the curing process of harvested tobacco leaves. Nitrosamines that form on tobacco are generally referred to as tobacco specific nitrosamines (TSNA) and are believed to be the result of a chemical reaction between tobacco alkaloids and oxides of nitrogen, more specifically, nitrites.
Green tobacco, or tobacco prior to harvesting and immediately after harvesting, is known to contain virtually no nitrosamines. In air-cured tobacco, the appearance of nitrosamines occurs at the end of yellowing, about 14 days into curing. The reaction between the oxides of nitrogen and the tobacco alkaloids which are generally amines are believed to be caused by the presence of bacteria which occur naturally on the leaves. These bacteria contain enzymes referred to as nitrate reductase. The enzyme is thought to convert the naturally occurring nitrate to nitrite under anaerobic conditions.
It is known that certain compounds when added to ground, air-cured tobacco in solution and incubated for a period of time, can inhibit the formation of nitrosamines. Included in these compounds is ferulic acid.
Conventionally, tobacco is harvested by cutting the stalks of tobacco in the field or plucking the whole leaves from the stalks as they become ripe. After harvesting, the leaves or stalks which bear the leaves are cured by drying, typically in an aerated barn, for a period of 1 to 6 weeks at a temperature of 20 to 70° C. After curing, the leaves are fermented by storing them for an extended period of time at a somewhat elevated temperature. Some tobacco is cured with smoke, such tobacco is referred to as Dark Fire Cured or Fire Cured Tobacco.
Nitrosamines are alleged as being carcinogenic and it is desirable to reduce nitrosamines in cured tobacco.